SONY CMOS Image Sensor Testing for Soft X-ray Detection

CMOS image sensors are active pixel sensors that allows for faster read-out speed per photon than traditional CCD image sensors. CMOS sensors are widely used in applications requiring short exposures such as accurate X-ray detection. Measuring CMOS sensitivities in different regions of the x-ray spectrum can determine whether it is suitable for high-precision astrophysics measurements in space. I worked with Dr. Miller’s group to build an experimental setup and characterize the X-ray data collection from commercial CMOS image sensors.

I constructed an active cooling sensor stand in the vacuum chamber for a CMOS sensor. Cooling the sensor to lower temperature can decrease the bias noise on the frames taken, and better simulate conditions in space. We were able to confirm that the bias noise was reduced as a result of operating on the cooling stand and found a linear relationship between temperature and noise. After setting up the experiment apparatus, I used a Fe-55 X-ray source to determine a Gaussian fit for the Fe K-alpha and K-beta lines with known energy peaks. With this, we were able to find the gain and energy conversion of the CMOS sensor. Additionally, we designed and constructed a Polonium Teflon-florenscence soft X-ray source, and more data was collected with the Polonium source to investigate the sensor performance at low energies.